Commit 2b26f0aa authored by Marco Elver's avatar Marco Elver Committed by Peter Zijlstra
Browse files

perf: Support only inheriting events if cloned with CLONE_THREAD 



Adds bit perf_event_attr::inherit_thread, to restricting inheriting
events only if the child was cloned with CLONE_THREAD.

This option supports the case where an event is supposed to be
process-wide only (including subthreads), but should not propagate
beyond the current process's shared environment.

Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarMarco Elver <elver@google.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/lkml/YBvj6eJR%2FDY2TsEB@hirez.programming.kicks-ass.net/
parent 47f661ec

include/linux/perf_event.h

+3 −2
Original line number Diff line number Diff line
@@ -958,7 +958,7 @@ extern void __perf_event_task_sched_in(struct task_struct *prev, 
				       struct task_struct *task);

extern void __perf_event_task_sched_out(struct task_struct *prev,

					struct task_struct *next);

extern int perf_event_init_task(struct task_struct *child);

extern int perf_event_init_task(struct task_struct *child, u64 clone_flags);

extern void perf_event_exit_task(struct task_struct *child);

extern void perf_event_free_task(struct task_struct *task);

extern void perf_event_delayed_put(struct task_struct *task);
@@ -1449,7 +1449,8 @@ perf_event_task_sched_in(struct task_struct *prev, 
static inline void

perf_event_task_sched_out(struct task_struct *prev,

			  struct task_struct *next)			{ }

static inline int perf_event_init_task(struct task_struct *child)	{ return 0; }

static inline int perf_event_init_task(struct task_struct *child,

				       u64 clone_flags)			{ return 0; }

static inline void perf_event_exit_task(struct task_struct *child)	{ }

static inline void perf_event_free_task(struct task_struct *task)	{ }

static inline void perf_event_delayed_put(struct task_struct *task)	{ }

include/uapi/linux/perf_event.h

+2 −1
Original line number Diff line number Diff line
@@ -389,7 +389,8 @@ struct perf_event_attr { 
				cgroup         :  1, /* include cgroup events */

				text_poke      :  1, /* include text poke events */

				build_id       :  1, /* use build id in mmap2 events */

				__reserved_1   : 29;

				inherit_thread :  1, /* children only inherit if cloned with CLONE_THREAD */

				__reserved_1   : 28;



	union {

		__u32		wakeup_events;	  /* wakeup every n events */

kernel/events/core.c

+14 −7
Original line number Diff line number Diff line
@@ -11653,6 +11653,9 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr, 
	    (attr->sample_type & PERF_SAMPLE_WEIGHT_STRUCT))

		return -EINVAL;



	if (!attr->inherit && attr->inherit_thread)

		return -EINVAL;



out:

	return ret;
@@ -12873,12 +12876,13 @@ static int 
inherit_task_group(struct perf_event *event, struct task_struct *parent,

		   struct perf_event_context *parent_ctx,

		   struct task_struct *child, int ctxn,

		   int *inherited_all)

		   u64 clone_flags, int *inherited_all)

{

	int ret;

	struct perf_event_context *child_ctx;



	if (!event->attr.inherit) {

	if (!event->attr.inherit ||

	    (event->attr.inherit_thread && !(clone_flags & CLONE_THREAD))) {

		*inherited_all = 0;

		return 0;

	}
@@ -12910,7 +12914,8 @@ inherit_task_group(struct perf_event *event, struct task_struct *parent, 
/*

 * Initialize the perf_event context in task_struct

 */

static int perf_event_init_context(struct task_struct *child, int ctxn)

static int perf_event_init_context(struct task_struct *child, int ctxn,

				   u64 clone_flags)

{

	struct perf_event_context *child_ctx, *parent_ctx;

	struct perf_event_context *cloned_ctx;
@@ -12950,7 +12955,8 @@ static int perf_event_init_context(struct task_struct *child, int ctxn) 
	 */

	perf_event_groups_for_each(event, &parent_ctx->pinned_groups) {

		ret = inherit_task_group(event, parent, parent_ctx,

					 child, ctxn, &inherited_all);

					 child, ctxn, clone_flags,

					 &inherited_all);

		if (ret)

			goto out_unlock;

	}
@@ -12966,7 +12972,8 @@ static int perf_event_init_context(struct task_struct *child, int ctxn) 


	perf_event_groups_for_each(event, &parent_ctx->flexible_groups) {

		ret = inherit_task_group(event, parent, parent_ctx,

					 child, ctxn, &inherited_all);

					 child, ctxn, clone_flags,

					 &inherited_all);

		if (ret)

			goto out_unlock;

	}
@@ -13008,7 +13015,7 @@ static int perf_event_init_context(struct task_struct *child, int ctxn) 
/*

 * Initialize the perf_event context in task_struct

 */

int perf_event_init_task(struct task_struct *child)

int perf_event_init_task(struct task_struct *child, u64 clone_flags)

{

	int ctxn, ret;
@@ -13017,7 +13024,7 @@ int perf_event_init_task(struct task_struct *child) 
	INIT_LIST_HEAD(&child->perf_event_list);



	for_each_task_context_nr(ctxn) {

		ret = perf_event_init_context(child, ctxn);

		ret = perf_event_init_context(child, ctxn, clone_flags);

		if (ret) {

			perf_event_free_task(child);

			return ret;

kernel/fork.c

+1 −1
Original line number Diff line number Diff line
@@ -2078,7 +2078,7 @@ static __latent_entropy struct task_struct *copy_process( 
	if (retval)

		goto bad_fork_cleanup_policy;



	retval = perf_event_init_task(p);

	retval = perf_event_init_task(p, clone_flags);

	if (retval)

		goto bad_fork_cleanup_policy;

	retval = audit_alloc(p);